Hammer mill having a rigid, removable eccentrically disposed screen



y 7, 1965 J. G. BRYANT 3,196,915

HAMMER MILL HAVING A RIGID, REMOVABLE ECCENTRICALLY DISPOSED SCREEN Filed Oct. 29, 1962 3 Sheets-Sheet 1 INVENTOR.

James 6. 81404407 J. G. BRYANT 3,196,915 HAMMER MILL HAVING A RIGID, REMOVABLE ECCENTRICALLY July 27, 1965 DISPOSED SCREEN Filed 001;. 29, 1962 3 Sheets-Sheet 2 GE 2.1mm

INVENTOR.

T4045: 6. BRYAN? Arraovzrd 3,196,915 CALLY J- G. BRYANT HAMMER MILL HAVING A RIGID, REMOVABLE EGCENTRI DISPOSED SCREEN July 27, 1965 3 Sheets-Sheet 3 Filed Oct. 29. 1962 3,196,915 HAME ZER Mill. HAVENG A RlGlD, REMQVABLE E CiCi-ENTREQALLY DKSPQSED SCREEN Senses G. Bryant, Bryant Engineering Company, 15% ltlth Ave, lort Huron, Mich. Filed Get. 29, 1962, her. No. 233,634 12 tllaims. (-Ci. 146-79) This invention relates to a hammer mill.

It is an object of this invention to provide a hammer mill which has a relatively large capacity in relation to its size.

A further object of the invention is to provide a hammer mill provided with a screen that does not require flexing for its removal and replacement so that the screen can be formed of a heavy rigid material and is therefore adaptable for grinding whole ears of corn, corn cobs and other relatively heavy materials.

A further object of the invention is to provide a hammer mill incorporating the above described features and at the same time enabling the screen to be safely removed and replaced with another screen without stopping the operation of the hammer mill.

a the drawings:

PEG. 1 is a perspective view of a hammer mill according to the present invention.

PEG. 2 is a sectional view along the line 2-45 in FIG. 1.

MG. 3 is a sectional view similar to P16. 2 and showing the csition of the screen at two progressive positions of removal.

FIG. 4- is a sectional view along the line 4-4 in 2 and showing the cradle structure for the screen.

Referring to FIG. 1, the hammer mill of the present invention comprises a housing all in which is journallcd rotor 12, the rotor being rigidly secured to a shaft l4- which is journalled on the housing by means of bearin s, one of which is shown at Shaft 14 is driven by a suitable motor, not illustrated. Housing to comprises a pair of side walls l3, Zii, a rear wall 22 and a front cover section 24. The upper end of housing ill is reinforced by a rectangular angle iron frame 26 which delines the upper end of the inlet hopper 23 of the hammer mill. In most instances, a chute 343 will be mounted on housing to communicate with inlet opening Preferably, the rear wall 22 has a replaceable wear plate 32 attached to the inner side thereof.

The lower end of the housing includes a dischar e chute as which is defined by the two side walls 13, 20 of the 13*, at the rout hy a short inclined wall 36 and at rear by two oppositely inclined walls 3%, so. At the upper end of wall A l the housing is reinforced by a solid cross bar 52 anchored at each end on the side walls of the housing. Referring specifically to FIG. 1, the front edges of side walls iii, 2% are inclined upwardly and reaiwardly and are flanged as by means of angle irons id which provide supports to which the cover 24 may be secured as by screws as.

ie specific rotor 12 shown in the drawings comprises a plurality of spaced discs iii which pivotally support around their periphery a plurality of hammers so. This form of rotor is shown merely for purposes of illustration, the invention in its broader aspects employing a rotor of any conventional form.

F.cferr*it1. ot FIG. 2, it will be noted that the housing i around the periphery of rotor 12 comprises generally three portions; namely, an inlet portion defined by the inlet hopper section 2%, the cover portion 24 and around the lower side of the rotor, the outlet portion which establishes communication between the rotor chamber 52 and the discharge chute 34. This outlet portion is covered by a screen 54. Screen 54 is formed from a rigid as distinguished from a flexible material and retains the shape nited States Patent tion as viewed in PEG.

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illustrated in the drawings. Screen 5 is located and positioned in the housing along its radically inner side by a pair of guide rails one on each side Wall of the housing. Around its radially outer side, screen $4 is located and supported by a cradle 53. Cradle 5% comprises a plurality of four axially spaced circular segment bars 6-3 which are interconnected by a plurality of cross bars 625. Cradle is pivotally supported on the two side walls of housing by threaded studs The cradle is designed to be pivotally actuated by rotating a handle 66 (FIGS. 1 and 4) fixed to a rock shaft as journalled on the side walls of housing it). At approximately the center thereof, shaft has a short link ill fixed thereto as by welding. The free end of link '76) is pivotally connected at H with a longer link 7'2 which is pivotally supported as at 73 by a bearing clock is. Block 74 is welded or otherwise fixed on a fiat cross bar is which inter onnects t e lower or free ends of the circular segment bars es of the cradle.

in Fi l 2, the toggle linkage formed by the links 7 ll, '72 is shown in the locked position wherein the handle 66 is pivoted downwardly to its lowermost position so that the links M, 73 urge the bar '76 and the spaced bearing blocks is; secured thereto upwardly in a counterclockwise direc- 2. it will be noted that the forward edge of screen 5'4. is in end abutting relation as at 8% with the lower edge of cover M This forward edge of the Av. screen has a handle 82 bolted thereon, the handle being in the form of an angle iron. The handle projects outwardly beyond the end of the screen and thus, in the locked position of the screen, overlaps the lower edge of cover Thus, in the locked position of the toggle linkage 'lti, '72, cross bar is with its bearing blocks 78 bears upwardly against handle 32 to form a tight sealed connection between the screen handle 22 and cover 24. It will also be observed that the end portion 34 of each inner screen guide is located slightly radially inwardly relative to the remainder of the screen guide so that the pressure exerted by the toggle linkage 7d, 72 is utilized exclusively in forming a tight sealed connection between the screen handle and cover it is to be understood, of course, that the linkage 7d, 72 is permitted to shitf to the overcenter locked position illustrated in PEG. 2 by reason of the flexing of shaft 68.

Referring to FIGS. 2 and 4, the end of shaft 63 opposite handle 6&5 is iournalled in the side wall Ztl of housing it) in a hole as which is generally the same diameter as shaft However, in order to withdraw rock shaft 68 from within the housing for servicing wtih the short link 7t} welded thereto, the side wall it} of the housing has an aperture slightly larger than link '76). This end of the rock shaft is journalled on a bearing plate ht) which is bolted to side wall 16, the holes 92 for the bolts being elongated slightly as shown in FIG. 2 so as to permit adjustment of the locking pressure when handle 66 is actuated. Rock shaft 68 is fixed against lengthwise shifting by bushings @3.

Still referring to FIG. 2, it will be observed that the radially outer ends of hammers so are located relatively close to the inner surface of cover 24 and the inner surface of screen 54-. ft is necesstary that the ends of those hammers travel in a circular path relatively close to the cover and the screen so that there will be little or no tendency for the holes in the screen to become plugged. The fineness of the finished product is regulated by the size of the holes in the screen. For fine grinding or pulverizing grain, a screen with small holes will be employed and unless the screen is spaced closely to the path of travel of the ends of the hammers on the rotor, the holes in the screen will tend to become plugged.

In the machine of this invention, cover 24 is concentric with the axis of the rotor shaft 14. However, in order to as obtain the maximum size screen and in order to permit this screen to be rigid and yet safely removed from the hous ing, screen 54 is formed as a cylindrical segment which has its axis at 94, shifted slightly from the axis 96 of the rotor shaft upwardly and toward cover 24. Thus, as will be apparent from the showing in FIG. 2, the radius of screen 54 is slightly greater than the radius of cover 24. This difference in radii facilitates removal of the screen from the housing and promotes the maintenance of a large size outlet for the hammer mill.

Referring to FIG. 3, the screen 54 is adapted to be withdrawn from the housing through an opening 93 between the lower end of cover 24 and a plate extending transversely across the housing at the upper edge of the inclined forward wall 36. From the standpoint of safety, the opening 98 should be as narrow as possible. This is true because in many instances, it becomes necessary to change screens in a hammer mill while the rotor is still rotating. Under such condition of operation, it is desirable to have any opening in the hammer mill housing as small as possible so that the likelihood of the operator being struck by any particles, etc. discharged by the rotor through the screen outlet is minimized. In the particular arrangement illustrated in the drawings, the width of opening or slot 98 is minimized by making the radius of screen 54 slightly greater than cover 24. However, the pulverizing action is not sacrificed in any way because the cradle 58 is designed to position the screen 54 with its axis at 94 so that it is in end abutting relation with the cover 24 and extends generally as a continuation of the circle defined by cover 24. The screen is thus located closely adjacent the path of travel of the outer ends of the hammer 50 on the rotor.

To withdraw the screen from the housing, it is only necessary to pivot handle 65 upwardly to the broken line position shown in FIG. 3 and then rotate the screen out of opening 98. When handle 66 is rotated to the unlocked position, it will be observed that cradle 58 pivots downwardly about its pivot support at 64 so that the screen 54 is released from its clamped position. Then, by drawing upwardly and slightly forwardly on the screen handle 82, the operator can withdraw the screen 54 through the opening 98 and slide it over the outer surface of cover 24. Since the screen has a slightly larger radius than cover 24, the screen more or less rides snugly against the outer surface of cover 24 as illustrated by the broken line showing at 102 in FIG. 3. It will be appreciated that to accomplish this withdrawal of the screen, it is only necessary that the slot 98 have a width only slightly greater than the thickness of the screen at the handle end as increased by the heads of the screws 104 which secure the handle 82 to the screen. To facilitate complete removal of the screen from within the housing, the upper end of cover 24 is fashioned with a tapered rib 166. When the screen 54 is shifted upwardly to the position shown in full lines in FIG. 3, the upper end of the screen is raised out of contact with the cover 24 so that the operator may grasp the screen firmly at its opposite edges to completely lift it out of the housing through slot 98.

The screen may be replaced by simply reversing the operation described; namely, initially positioning the screen as shown in solid lines in FIG. 3 and thereafter progressively revolving it in a clockwise direction between the inner guide 56 and the arcuate bar 60 of the cradle until it assumes a position wherein the handle 82 engages the flat bar 190. Thereafter, handle 66 is pivoted downwardly in a clockwise direction as viewed in FIGS. 2 and 3 to clamp the screen in place as illustrated in FIG. 2. With the screen locked in place, it will be observed that the slot 98 is completely closed by handle 82, cross bar 76 and the flexible sealing strip 168 secured to cross bar '76 and adapted to engage the inner side of bar 10% when the screen is locked in its operative position by the toggle linkage.

The sealing engagement of strip 1&8 may be enhanced 4 by a felt strip on the inside of bar 1%. Likewise, the proper engagement of the toggle operated lock may be facilitated by relieving the screen engaging face of blocks '78 as at 112.

Thus, it will be seen that the hammer mill of this invention possesses several desirable features. The design of the machine is such that the screen can be removed from its operative position through a relatively narrow opening in the housing without requiring flexing of the screen. Thus, the screen is adapted to be made from a rigid material so as to be capable of handling heavy loads. At the same time, the screen is designed so that it is fairly concentric with the axis of rotation of the rotor and positioned closely adjacent the path of travel of the ends of the rotor. In view of this specific arrangement, a reasonably narrow slot for the removal of the screen can be provided and the operator will therefore not be subjected to hazardous conditions when the screen is removed.

I claim:

1. A hammer mill comprising a housing having a hammer mill rotor journalled for rotation therein on a horizontal axis, said housing being divided generally into three portions around the periphery of said rotor, namely, an inlet portion through which the material to be processed is directed to the rotor, an outlet portion through which the process material is discharged and a peripherally closed portion, said peripherally closed portion comprising a generally cylindrical cover portion extending around and closely adjacent the outer periphery of the rotor, a generally rigid cylindrically shaped screen covering said outlet portion, said screen at one end being circumferentially contiguous to one end of said cover portion of the housing and having a radius slightly greater than the radius of said cylindrical cover portion, said screen extending across said outlet opening closely adjacent the periphery of the rotor and being eccentric with respect to the axis of rotation of the rotor when in operative position, said housing having a narrow, horizontally extending opening therein adjacent the circumferentially contiguous ends of said screen and said cover portion, said screen having a handle portion projecting through said opening and the opening enabling the screen to be withdrawn therethrough in an arcuate path overlying the outer arcuate surface of the cylindrical portion of the housing and having a width only substantially sufficient to permit such withdrawal of the screen.

2. A hammer mill as called for in claim 1 wherein one end of the screen abuts circumferentially in end to end relation against the adjacent end of the cover portion of the housing, said adjacent ends of the screen and cover portion having a generally common tangent, and including means for locking said screen in said position.

3. A hammer mill as set forth in claim 1 wherein the circumferential extent of said screen is at least as great as the circumferential extent of said cover portion of the housing.

4. A hammer mill as set forth in claim 1 wherein the circumferential extent of said screen is at least as great as the circumferential extent of said inlet opening and at least as great as the circumferential extent of said cover portion of the housing.

5. A hammer mill comprising a housing having a rotor journalled therein, said housing having a discharge chute extending from the periphery of the rotor, said discharge chute being closed at the periphery of the rotor by a screen, said screen being formed generally as a segment of a cylinder and being rigid as distinguished from flexible, said housing having a cylindrical wall circumferentially adjacent one end of the screen and forming an arcuate extension of said screen, said screen having a radius slightly larger than the radius of said cylindrical Wall, and when in the operative position being slightly eccentric with respect to the axis of rotation of the rotor, said housing having a narrow opening adjacent the adjoining ends r of the screen and cylindrical side wall through which the screen may be withdrawn, said opening having a width substantially only sufficient to permit the screen to be withdrawn from the housing by revolving the screen outwardly through said opening and over the outer surface of said cylindrical side wall.

6. A hammer mill as called for in claim 5 including a cradle extending around and supporting said screen, said cradle being pivotally supported at one end adjacent the opposite end of said screen when in operative position and means connected with the other end of said cradle for actuating the cradle and locking the screen in said operative position, said locking means including a sealing member which, when the locking means are in the locked position, engages a portion of the housing and cooperates with the screen to seal said opening.

'7. A hammer mill as called for in claim 5 wherein said one end of the screen and the adjacent end of said cylindrical wall are in end to end abutting relation, and the screen is positioned such that it forms a smooth continuation of curve established by the cover.

8. A hammer mill as called for in claim 5 wherein said cylindrical wall is generally concentric with the axis of rotation of the rotor and wherein the center of curvature of the screen when in operative position is ofiset from the axis of rotation of the rotor in a direction away from said screen and toward said cylindrical wall.

9. A hammer mill as called for in claim 5 wherein said screen has a handle portion extending through said openmg.

19. A hammer mill as called for in claim 9 wherein said cylindrical wall has an inclined rib member thereon adjacent the end thereof remote from said opening for raising the handle end of the screen from the outer surface of the cylindrical wall as the handle end of the screen approaches said remote end of the cylindrical wall.

11. A hammer mill as called for in claim 5 including means for locking said screen in its operative position, said locking means including a sealing member which, when the locking means are in locked position, engages a portion of the housing and cooperates with the screen to seal said opening.

12. A hammer mill as called for in claim 5 wherein the screen has a circumferential extent at least as great as the circumferential extent of said cylindrical wall.

References Cited by the Examiner UNITED STATES PATENTS 1,697,297 1/29 Williams 241-89 1,828,490 10/31 Clement 241-86 XR 2,360,892 10/44 Rench et al. 241-89 2,419,773 4/47 Gruendler 241-89 2,532,262 11/50 Schutte et al 241-86 2,557,344 6/51 Erickson 241-86 XR 2,669,396 2/54 Nickle 241-89 2,823,869 2/58 Reese et al 241-89 J. SPENCER OVERHOLSER, Primary Examiner. 

1. A HAMMER MILL COMPRISING A HOUSING HAVING A HAMMER MILL ROTOR JOURNALLED FOR ROTATION THEREIN ON A HORIZONTAL AXIS, SAID HOUSING BEING DIVIDED GENERALLY INTO THREE PORTIONS AROUND THE PERIPHERY OF SAID ROTOR, NAMELY, AN INLET PORT THROUGH WHICH THE MATERIAL TO BE PROCESSED IS DIRECTED TO THE ROTOR, AN OUTLET PORTION THROUGH WHICH THE PROCESS MATERIAL IS DISCHARGED AND A PERIPHERALLY CLOSED PORTION, SAID PERIPHERALLY CLOSED PORTION COMPRISING A GENERALLY CYLINDRICAL COVER PORTION EXTENDING AROUND SAID CLOSELY ADJACENT THE OUTER PERIPHERY OF THE ROTOR, A GENERALLY RIGID CYLINDRICALLY SHAPED SCREEN COVERING SAID OUTLET PORTION, SAID SCREEN AT ONE END BEING CIRCUMFERENTIALLY CONTIGUOUS TO ONE END OF SAID COVER PORTION OF THE HOUSING AND HAVING A RADIUS SLIGHTLY GREATER THAN THE RADIUS OF SAID CYLINDRICAL COVER PORTION, SAID SCREEN EXTENDING ACROSS SAID OUTLET OPENING CLOSELY ADJACENT THE PERIPHERY OF THE ROTOR AND BEING ECCENTRIC WITH RESPECT TO THE AXIS OF ROTATION OF THE ROTOR WHEN IN OPERATIVE POSITION, SAID HOUSING HAVING A NARROW, HORIZONTALLY EXTENDING OPENING THEREIN ADJACENT THE CIRCUMRERENTIALLY CONTIGUOUS ENDS OF SAID SCREEN AND SAID COVER PORTION, SAID SCREEN HAVING AN HANDLE PORTION PROJECTING THROUGH SAID OPENING AND THE OPENING ENABLING THE SCREEN TO BE WITHDRAWN THERETHROUGH IN AN ARCUATE PATH OVERLYING THE OUTER ARCUATE SURFACE OF THE CYLINDRICAL PORTION OF THE HOUSING AND HAVING A WIDTH ONLY SUBSTANTIALLY SUFFICIENT TO PERMIT SUCH WITHDRAWAL OF THE SCREEN. 